Díaz directed and released her first feature film, Tanikala (Chains) in 1980. Since then, she has been one of the most active and visible directors in Philippine cinema.[2]

Her early films Brutal, Karnal (Of the Flesh), and Alyas Baby Tsina, sharply condemn the oppressive social system during the administration of Philippine President Ferdinand Marcos. When the Marcos was deposed in 1986, Diaz left filmmaking.[2]

Díaz produced television programs for several years. Her work attempts to reflect the social and political problems to attain social reform. She admittedly uses her work as a tool to uphold, promote, and protect the state of democracy in the Philippines.[2]

In 1995, she again directed films, beginning with the release of Ipaglaban Mo (Redeem Her Honor). She continued directing such films as May Nagmamahal Sa Iyo (Madonna and Child), Sa Pusod Ng Dagat (In the Navel of the Sea), José Rizal, and Muro Ami (Reef Hunters). Her body of work is a continuous examination of difficult social problems in the country. Her works often deal with the lives of the Filipino poor, women, and children who struggle to survive under harsh conditions.[2]

Arguably her most famous work, José Rizal, featured actor and 2007 Philippine senatorial candidate César Montano playing the national hero as an ordinary human being, artist, and struggling doctor.[2]

A Japanese award-giving body described her body of work to be "harmoniously blending entertainment, social consciousness, and ethnic awareness." The organization continued by saying: "(Her work) has won acclaim both in the Philippines and abroad for its high level of artistic achievement. It is an ideal manifestation of the artistic culture of Asia, and so is most deserving of the Arts and Culture Prize of the Fukuoka Asian Culture Prizes."[3]

Díaz is the 2001 Laureate of the Fukuoka Prize for Culture and the Arts in Japan. She has won numerous directing awards from award-giving bodies such as the Metro Manila Film Festival, the Urian Awards, the Film Academy of the Philippines, the Famas Awards, the Star Awards, the Catholic Mass Media Awards the British Film Institute Award, the International Federation of Film Critics Award (FIPRESCI), and the Network of Pan Asian Cinema Award (NETPAC).[2]

1980: Brutal (Brutal), written by Ricky Lee, produced by Bancom Audiovision, starring Amy Austria, Jay Ilagan, Johnny Delgado, Charo Santos; multi-awards from the 1980 Metro Manila Film Festival, Film Academy of the Philippines, FAMAS; exhibited at the PIA Film Festival, Tokyo.

1982: Moral (Moral), written by Ricky Lee, produced by Seven Star Productions, starring Lorna Tolentino, Gina Alajar, Sandy Andolong, Ana Marin, Laurice Guillen; rated A by the Film Ratings Board; 1984 British Film Institute Outstanding Film of the Year.

1986: "Four Days In February" (about the 4-day People Power Revolution, in EDSA); shelved due to political reasons.

1990: "Victory Boy" (about the presence of US Bases in the Philippines; particularly the US Naval Base, in Subic, Olongapo City); supposed to star then Senator Joseph Ejercito Estrada and Philippine superstar Nora Aunor; shelved due to political reasons; discontinued when the US Military Bases were removed in 1991.